The present invention relates to high-accuracy optical spectrum analyzers in a new arrangement for carrying out several simultaneous measurements at several signal sources.
In the area of optical communications technology, optical spectrum analyzers are used whose principal areas of application are the characterization of the optical components and the monitoring of optical transmission paths. Optical spectrum analyzers which according to the Littman design comprise a corner prism as a deviation mirror and a common lens for the coupled and decoupled light, provide several advantages such as compact design and robust performance. A big disadvantage is the high retro-reflection to the input fiber, which during measuring of optical components or optical transmission systems can lead to erroneous readings. Such an optical spectrum analyzer is for example disclosed in U.S. Pat. No. 5,886,785.
Conventional optical spectrum analyzers, such as for example those known from EP 0 540 966 B1, have the further disadvantage in that the spectrum of only one source can be measured. If measurements from several sources are required, for example on different optical waveguides of a transmission system or in front of and behind an optical component, then clumsy and time-consuming reconnection of the waveguide, or else installation of an expensive optical switch, is necessary.
It is thus the object of the present invention to propose an option which provides for simultaneous measurement of several optical spectra.
According to the invention this object is met by using an optical arrangement in an optical spectrum analyzer according to the features set out below. The present invention comprises the use of an optical arrangement comprising a device for coupling several light rays; a collimator for generating parallel bundles of light from the diverging light rays arriving from the device for coupling; a device for dispersing the impinging light rays along a dispersion axis; a deviation device for guiding the dispersed light rays offset in relation to the light rays coming from the dispersion device, for a second time to the dispersion device; a focusing device for focusing the light rays impinging from the dispersion device onto a device for decoupling the light rays, in an optical spectrum analyzer with several inlet and outlet apertures, arranged offset, perpendicular to the dispersion axis of the dispersion device, for simultaneous analysis of several optical spectra, in that the light rays entering via the inlet apertures, of which there are several, independently of each other pass through the arrangement and exit via the outlet apertures and in that the optical performance of the decoupled wavelengths of the light rays is measured simultaneously. Further advantageous embodiments are set out hereinbelow.